pytorch - 💡(How to fix) Fix PyTorch 2.12 compile error: Boolean literal getting used as LHS expression

def forward(self, L_c_ : torch.Tensor, L_a_ : torch.Tensor, L_b_ : torch.Tensor):
    ...
    True &= ne;  iand = True;  ne = iand = None  # SYNTAX ERROR
    ...

---

import torch


@torch.compile
def mul(
    a: torch.Tensor,
    b: torch.Tensor,
    c: float | int | None,
) -> torch.Tensor:
    """
    a * b     ...if c == 0
    a * b + c ...otherwise
    """
    has_bias = c is not None
    has_bias &= c != 0.0

    if has_bias:
        return a * b + c

    return a * b


def main():
    a = torch.randn(10)
    b = torch.randn(10)

    """
    First call: success

    >>> # Generated code:
    >>> def forward(self, L_a_ : torch.Tensor, L_b_ : torch.Tensor):
    >>>     l_a_ = L_a_
    >>>     l_b_ = L_b_
    >>>     mul = l_a_ * l_b_;  l_a_ = l_b_ = None
    >>>     return (mul,)
    """
    _ = mul(a, b, c=0.0)


    """
    Second call: fails with syntax error

    >>> # Generated code:
    >>> def forward(self, L_c_ : torch.Tensor, L_a_ : torch.Tensor, L_b_ : torch.Tensor):
    >>>     l_c_ = L_c_
    >>>     l_a_ = L_a_
    >>>     l_b_ = L_b_
    >>>     item = l_c_.item();  l_c_ = None
    >>>     ne = item != 0.0
    >>>     True &= ne;  iand = True;  ne = iand = None  # SYNTAX ERROR
    >>>     mul = l_a_ * l_b_;  l_a_ = l_b_ = None
    >>>     add = mul + item;  mul = item = None
    >>>     return (add,)
    """
    _ = mul(a, b, c=0.5)


if __name__ == "__main__":
    main()

---

Traceback (most recent call last):
  File ".../compile_bug.py", line 27, in <module>
    out = mul(a, b, c=0.5)
  File ".../lib/python3.10/site-packages/torch/_dynamo/eval_frame.py", line 1047, in compile_wrapper
    result = fn(*args, **kwargs)
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 2474, in __call__
    result = self._torchdynamo_orig_backend(
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 2192, in __call__
    result = self._inner_convert(
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 736, in __call__
    result = _compile(
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 2025, in _compile
    raise InternalTorchDynamoError(
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 1961, in _compile
    guarded_code, tracer_output = compile_inner(code, one_graph, hooks)
  File ".../lib/python3.10/site-packages/torch/_utils_internal.py", line 96, in wrapper_function
    return function(*args, **kwargs)
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 1571, in compile_inner
    result = _compile_inner(code, one_graph, hooks)
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 16
30, in _compile_inner
    dynamo_output = compile_frame(
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 14
78, in compile_frame
    bytecode, tracer_output = transform_code_object(code, transform)
  File ".../lib/python3.10/site-packages/torch/_dynamo/bytecode_transformation.py", line 1626, in transform_code_object
    tracer_output = transformations(instructions, code_options)
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 1450, in transform
    tracer_output = trace_frame(
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 343, in _fn
    return fn(*args, **kwargs)
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 911, in trace_frame
    run_tracer()
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 892, in run_tracer
    tracer.run()
  File ".../lib/python3.10/site-packages/torch/_dynamo/symbolic_convert.py", line 1813, in run
    while self.step():
  File ".../lib/python3.10/site-packages/torch/_dynamo/symbolic_convert.py", line 1480, in step
    self.dispatch_table[inst.opcode](self, inst)
  File ".../lib/python3.10/site-packages/torch/_dynamo/symbolic_convert.py", line 5143, in RETURN_VALUE
    self._return(inst)
  File ".../lib/python3.10/site-packages/torch/_dynamo/symbolic_convert.py", line 5125, in _return
    all_stack_locals_metadata = self.output.compile_subgraph(
  File ".../lib/python3.10/site-packages/torch/_dynamo/output_graph.py", line 2113, in compile_subgraph
    self.compile_and_call_fx_graph(tx, pass2.graph_output_vars(), root)
  File ".../lib/python3.10/site-packages/torch/_dynamo/output_graph.py", line 2628, in compile_and_call_fx_graph
    fx.GraphModule(root, self.graph),
  File ".../lib/python3.10/site-packages/torch/fx/graph_module.py", line 578, in __init__
    self.graph = graph
  File ".../lib/python3.10/site-packages/torch/nn/modules/module.py", line 2074, in __setattr__
    super().__setattr__(name, value)
  File ".../lib/python3.10/site-packages/torch/fx/graph_module.py", line 634, in graph
    self.recompile()
  File ".../lib/python3.10/site-packages/torch/fx/graph_module.py", line 933, in recompile
    cls.forward = _forward_from_src(self._code, python_code.globals, co_fields)
  File ".../lib/python3.10/site-packages/torch/_dynamo/convert_frame.py", line 255, in fx_forward_from_src_skip_result
    result = original_forward_from_src(src, globals, co_fields)
  File ".../lib/python3.10/site-packages/torch/fx/graph_module.py", line 110, in _forward_from_src
    return _method_from_src(
  File ".../lib/python3.10/site-packages/torch/fx/graph_module.py", line 120, in _method_from_src
    _exec_with_source(src, globals_copy, co_fields)
  File ".../lib/python3.10/site-packages/torch/fx/graph_module.py", line 106, in _exec_with_source
    exec(compile(src, key, "exec"), globals)
torch._dynamo.exc.InternalTorchDynamoError: SyntaxError: 'True' is an illegal expression for augmented assignment (<eval_with_key>.2, line 10)